The value of image display for conditioning the psychological state, physiological state, or overall behavior of a human subject is widely recognized and documented, with applications in numerous fields. In health-related fields such conditioning can be used for purposes such as stress management as well as for helping in the treatment of conditions such as anxiety, brain injury, or stroke, and other psychological and physiological conditions. In behavioral sciences, such conditioning can be applied to behavior modification, for example. In training applications, conditioning the psychological state, physiological state, or overall behavior of a human subject can be useful in conjunction with simulation systems. In entertainment fields, such conditioning, coupled with careful measurement techniques, could be used to adapt a visual entertainment experience to suit a particular human subject.
For the purpose of this application, it is instructive to clarify the meaning of the verb “condition” as used herein with reference to prior art devices as well as to the present invention. The verb “condition” is broadly defined in the Merriam-Webster Collegiate Dictionary as “to adapt, modify, or mold so as to conform to an environing culture” or “to modify so that an act or response previously associated with one stimulus becomes associated with another.” Using this sense, the present invention is directed to an apparatus and method for conditioning the psychological state, physiological state, or behavior of a human subject by displaying images to a subject, measuring the subject's response, and adapting further display operation based upon the measured response of the subject. In broadest terms, the present invention is directed to apparatus and methods solutions in health management, stress management, training, and entertainment. It is also instructive to observe that, in the broad sense used in this application, the concept of conditioning the psychological state of a subject encompasses that of modifying the physiological state or the behavioral response of the subject.
An area of particular interest in conditioning the psychological or physiological state of a subject relates to the measurement and management of stress. The measurement and management of a psychological and physiological state, such as the stress, of a subject is a component of a health management program. In order to manage stress, which can have both a psychological and physiological component, it is useful to measure a physiological state of a subject. Useful types of measurements can include measuring galvanic skin response, temperature of fingers, toes, or other extremities, electromyographic (EMG) signals, electroencephalographic (EEG) signals, heart rate, blood pressure, etc., to determine the stress level or level of anxiety of the subject. Dilation of the eye pupil can also be a useful indicator of stress level. The results of these measurements can be converted into signals and fed back as an indication of the subject's level of stress. The subject's level of stress can be determined, measured and compared to a predetermined base level, then converted into sound, light, heat, vibration or images and fed back to the subject.
Several methods for determining a change in stress levels are disclosed in U.S. Pat. No. 6,394,963 and commonly-assigned copending U.S. patent application Ser. No. 09/865,902. The subject in employing stress-reducing techniques uses sound, light, and images to help control stress response. Changes due to physical measures are shown to the subject by a biofeedback device by changing the sound, heat, vibration, light, or images. In the case of images, for example the initial state may show an image out of focus, then, as the stress level decreases, improving focus so that the image becomes more defined. In U.S. Pat. No. 5,465,729, measurements of electro-physiological quantities are used to control a presentation to a subject of a series of pre-stored audio-visual sequences. In this reference, the image does not have to provide feedback and can be used to achieve a relaxed state.
U.S. Pat. No. 3,855,998 shows an entertainment device that includes sensing means connected to the subject. In this reference, the sensing means can, for example, sense the subject's galvanic skin response and, according to the given measured state of the subject, provide a given type of audio-visual stimulation for a timed interval to hold the subject's attention or modify subject response to a desired state. At the end of the interval, the subject's state is again measured and a further timed audio-visual response, based on this measured state, is presented to the subject.
In U.S. Pat. No. 5,596,994, an automated and interactive positive motivation system is disclosed. The system of this arrangement permits a physician, counselor, or trainer to produce and send a series of motivational messages and/or questions to a subject to change or reinforce a specific behavioral response.
U.S. Pat. No. 6,149,586 discloses a system and method for diagnosing executive dysfunctions in patients using virtual reality (VR) technology. However, images shown to the subjects are displayed on a CRT monitor, constraining the capability of the system for achieving full engagement of the subject's attention.
Psychotherapists have found that mental visualization of images or guided imagery is a very effective tool for behavior modification therapy, an important factor in managing a subject's stress. Implementation of guided imagery based therapies can be hindered by variety of factors such as a subject's inability to create and properly control mental images and inability to practice and apply visualization techniques without assistance.
U.S. Pat. No. 6,102,846 discloses a system for managing a psychological and physiological state of a subject using images that are created according to a personalized preferred response profile and specifically tailored to the subject. The image display device disclosed in U.S. Pat. No. 6,102,846 is a high-resolution color monitor. However, as is noted above, display devices of this type are limited in providing realistic images. The subject can be too easily distracted and must exert some effort to become absorbed in the viewing experience with this type of display.
There is considerable interest in applying virtual reality (VR) imaging as part of behavior modification therapy, particularly for treatment of phobias and related neuroses. However, drawbacks with existing VR imaging techniques include cost and complexity, lack of realistic imaging, and an awkward viewing environment due to the need for the subject to wear goggles, headgear, or special glasses.
The potential value of auto stereoscopic display systems is widely appreciated particularly in entertainment and simulation fields. Auto stereoscopic display systems include “immersion” systems, intended to provide a realistic viewing experience for a subject by visually surrounding the subject with a three-dimensional image having a very wide field of view. As differentiated from the more general category of stereoscopic displays, the auto stereoscopic display is characterized by the absence of any requirement for a wearable item of any type, such as goggles, headgear, or special glasses, for example. That is, an auto stereoscopic display attempts to provide “natural” viewing conditions for a subject.
Conventional display systems, such as the type disclosed in U.S. Pat. No. 6,102,846, use a color display monitor or project an image onto a screen for viewing. Optically, this type of image is termed a “real” image, with some form of display surface positioned where the image is formed in space by the optical system. However, for realistic viewing in an immersive imaging system, display of a “virtual” image, as contrasted with a real image, has distinct advantages. A virtual image, formed by an optical system, appears to be more natural in appearance than a real image, with a more lifelike light behavior. A virtual image is not projected onto a surface and therefore does not exhibit screen or monitor artifacts. The virtual image appears to the eye as if it has a spatial position, but this appearance is caused by divergence of light rays rather than by the actual formation of a focused image. A very small source object can provide the scene content for a large virtual image. A display system using a curved mirror and beamsplitter such as is disclosed in U.S. Pat. No. 6,416,181 forms a virtual image that appears to be well behind the curved mirror in space. As a result, vergence and accommodation effects are improved over solutions using real image projection. Vergence refers to the degree at which the observer's eyes must be crossed in order to fuse the separate images of an object within the field of view. Vergence decreases, then vanishes as viewed objects become more distant. Accommodation refers to the requirement that the eye lens of the observer change shape to maintain retinal focus for the object of interest. It is known that there can be a temporary degradation of the observer's depth perception when the observer is exposed for a period of time to mismatched depth cues for vergence and accommodation. It is also known that this negative effect on depth perception can be mitigated when the accommodation cues correspond to distant image position, as can be provided using virtual imaging. In addition to providing an image that is easy for the eye to adapt to, virtual imaging allows a wide field of view.
It must be noted that, because of wide use of the term “virtual reality”, there is some confusion of terminology related to virtual images. In some contexts, virtual images are considered to be images that are solely computer-generated. However, for the purposes of the present application, references to “virtual images” refer to images formed optically in the manner described above and differentiated from real images. For the purposes of the present application, virtual image content may be either from natural sources or may be computer-generated. Virtual reality techniques may employ either real images, as is described with reference to U.S. Pat. No. 6,102,846 and U.S. Pat. No. 6,149,586 above, or may employ virtual images.
Pupil imaging also provides advantages for realistic autostereoscopic imaging. In pupil imaging, the eye pupil of the subject is optically conjugate to the projection lens pupil. This allows natural head movement if an eye-tracking and compensation mechanism is employed to adjust the viewing pupil position when the eye pupil is moved. With a system that updates the image display according to the position of left and right viewing pupils, some ability to “look around” an object can be achieved.
An acknowledged design goal for immersion systems is to provide the most realistic viewing environment possible. While this relates most pronouncedly to visual perception, it can also encompass auditory, tactile, and other sensory perception as well. It is well known to those skilled in the virtual reality art that, while the visual display is the primary component needed for an effective immersion experience, there is substantial added value in complementing visual accuracy with reinforcement using other senses of a subject. While the addition of auditory, tactile, and motion stimuli has been implemented for a more realistic and compelling motion picture experience to an audience, there is a need to provide additional sense stimuli in an auto stereoscopic viewing system. Moreover, the use of such additional stimuli may be optimized using sensed feedback information from measurements obtained from a subject.
Thus, it can be seen that, while there have been some conventional approaches for conditioning the psychological and physiological state of a subject using displays that provide real images, there is a need for solutions that provide a more natural and realistic viewing experience. In particular, there would be benefits to providing an improved auto stereoscopic imaging solution for viewing electronically processed images, where the solution provides a structurally simple apparatus, minimizes aberrations and image distortion, and meets demanding requirements for providing wide field of view with large pupil size, for compensating for subject head movement and interocular distance differences, and for providing additional sensory stimulation. At the same time, such a solution could serve as the basis for a system that enables a personalized image response profile to be developed and maintained for conditioning the psychological and physiological state of a subject or for conditioning a subject's behavior.